The roles of cysteine proteinases (CP) in leaf protein accumulation and composition were investigated in transgenic tobacco (Nicotiana tabacum L.) plants expressing the rice cystatin, OC-1. The OC-1 protein was present in the cytosol, chloroplasts, and vacuole of the leaves of OC-1 expressing (OCE) plants. Changes in leaf protein composition and turnover caused by OC-1-dependent inhibition of C...

BACKGROUND AND AIMS The amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) synthesized in a leaf is closely correlated with N influx into the leaf throughout its lifetime. Rubisco synthesis and N influx are most active in the young leaf during expansion, but are very limited in the senescent leaf. However, it is not established whether Rubisco synthesis can be obse...

There is a growing impetus in developing novel strategies to address global concerns regarding food security. As crop productivity gains through traditional breeding begin to lag and arable land becomes scarcer, it seems that we are heading for unsustainable global populations. It has been foreshadowed that global food production will need to rise more than 50% before 2050 to meet the ever-incr...

The lysate from intact chloroplasts mechanically isolated from primary leaves of 9 day old seedlings of wheat (Triticum aestivum L. var Aoba) was incubated in the pH range of 5.5 to 8.5 at 370C for 5 hours. Proteolytic activity against ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) was estimated by disappearance of the large subunit of Rubisco or the appearance of its de...

Little is known about the effect of hormones on the photosynthetic process. Therefore, we studied Rubisco content and expression along with gas exchange parameters in transgenic tobacco (Nicotiana tabacum) plants that are not able to sense ethylene. We also tested for a possible interaction between ethylene insensitivity, abscisic acid (ABA), and sugar feedback on photosynthesis. We measured Ru...

Ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) is responsible for the fixation of atmospheric CO2 in photosynthesis. Rubisco is not only the most abundant protein in nature but also one with a remarkably high chaperone requirement for folding, assembly and maintenance. The major form of Rubisco (form I) is hexadecameric, consisting of 8 large (RbcL) and 8 small (RbcS) subunits. The f...

The previous investigations show that the amount and activity of Rubisco appears the major limitation to effective C(4) photosynthesis at low temperatures. The chilling-tolerant and bioenergy feedstock species Miscanthus x giganteus (M. x giganteus) is exceptionally productive among C(4) grasses in cold climates. It is able to develop photosynthetically active leaves at temperatures 6 degrees C...

The sunlight-driven conversion of carbon dioxide into organic matter fuels nearly all life on Earth. The enzyme Rubisco catalyses the fixation of carbon dioxide in photosynthesis, and thereby serves as the entry point for inorganic carbon into the biosphere. Rubisco limits biomass accumulation when sunlight is plentiful, and has therefore been heavily targeted in bioengineering efforts to boost...

Rubisco activase is a nuclear-encoded chloroplast protein that is required for the light activation of ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) in vivo. In most plants examined to date, there are two isoforms of Rubisco activase arising from alternative splicing that differ only at the carboxyl terminus. Here we demonstrate with recombinant proteins that in Arabidopsis the larg...

Rubisco small subunits (RbcSs) are encoded by a nuclear multigene family in plants. Five RbcS genes, OsRbcS1, OsRbcS2, OsRbcS3, OsRbcS4, and OsRbcS5, have been identified in rice (Oryza sativa). Among them, the amino acid sequence of OsRbcS1 differs notably from those of other rice RbcSs. Phylogenetic analysis showed that OsRbcS1 is genetically distant from other rice RbcS genes and more closel...